<template>
  <div class="music-list">
    <div class="back" @click="back">
      <i class="icon-back"></i>
    </div>
    <h1 class="title" v-html="title"></h1>
    <div class="bg-image" :style="bgStyle" ref="bgImage">
      <div class="play-wrapper">
        <div ref="playBtn" v-show="songs.length > 0" class="play" @click="randomPlay">
          <i class="icon-play"></i>
          <span class="text">随机播放全部</span>
        </div>
      </div>
      <div class="filter" ref="filter"></div>
    </div>
    <div class="bg-layer" ref="layer"></div>
    <scroll
      @scroll="scroll"
      :listenScroll="listenScroll"
      :probeType="probeType"
      class="list"
      ref="list"
    >
      <div class="song-list-wrapper">
        <song-list :rank="rank" @select="selectSong" :songs="songs"></song-list>
      </div>
    </scroll>
  </div>
</template>

<script type="text/ecmascript-6">
import SongList from "./SongList";
import Scroll from "@/components/common/scroll/Scroll";
import { mapActions, mapGetters } from "vuex";

const RESOLVE_HEIGHT = 40;
export default {
  name: "MusicList",
  components: {
    Scroll,
    SongList,
  },
  props: {
    title: {
      type: String,
      default: "",
    },
    bgImg: {
      type: String,
      default: "",
    },
    songs: {
      type: Array,
      default: [],
    },
    rank: {
      type: Boolean,
      default: false
    }
  },
  data() {
    return {
      imgHeight: 0,
      scrollY: 0,
    };
  },
  computed: {
    bgStyle() {
      return `background-image:url(${this.bgImg})`;
    },
  },
  methods: {
    scroll(pos) {
      this.scrollY = pos.y;
    },
    back() {
      this.$router.back();
    },
    selectSong(song, index) {
      this.selectplay({
        list: this.songs,
        index,
      });
    },
    randomPlay() {
      this.randomplay({list:this.songs})
    },
    ...mapActions(["selectplay","randomplay"]),
  },
  created() {
    this.probeType = 3;
    this.listenScroll = true;
  },
  mounted() {
    this.imgHeight = this.$refs.filter.clientHeight;
    this.minTransalteY = -this.imgHeight + RESOLVE_HEIGHT;
  },
  watch: {
    scrollY(newVal) {
      let translateY = Math.max(this.minTransalteY, newVal);
      let zIndex = 0;
      let scale = 1;
      this.$refs.layer.style["transform"] = `translate3d(0,${translateY}px,0)`;
      const percent = Math.abs(newVal / this.imgHeight);
      if (newVal > 0) {
        scale = 1 + percent;
        zIndex = 10;
      }
      if (newVal < this.minTransalteY) {
        zIndex = 10;
        this.$refs.bgImage.style.paddingTop = 0;
        this.$refs.bgImage.style.height = `${RESOLVE_HEIGHT}px`;
        this.$refs.playBtn.style.display = "none";
      } else {
        this.$refs.bgImage.style.paddingTop = "70%";
        this.$refs.bgImage.style.height = 0;
        this.$refs.playBtn.style.display = "";
      }
      this.$refs.bgImage.style["transform"] = `scale(${scale})`;
      this.$refs.bgImage.style.zIndex = zIndex;
    },
  },
};
</script>

 
<style scoped lang="stylus" rel="stylesheet/stylus">
@import '~common/stylus/variable';
@import '~common/stylus/mixin';

.music-list {
  position: fixed;
  z-index: 100;
  top: 0;
  left: 0;
  bottom: 0;
  right: 0;
  background: $color-background;
}

.back {
  position: absolute;
  top: 0;
  left: 6px;
  z-index: 50;

  .icon-back {
    display: block;
    padding: 10px;
    font-size: $font-size-large-x;
    color: $color-theme;
  }
}

.title {
  position: absolute;
  top: 0;
  left: 10%;
  z-index: 40;
  width: 80%;
  no-wrap();
  text-align: center;
  line-height: 40px;
  font-size: $font-size-large;
  color: $color-text;
}

.bg-image {
  position: relative;
  width: 100%;
  height: 0;
  padding-top: 70%;
  transform-origin: top;
  background-size: cover;
}

.play-wrapper {
  position: absolute;
  bottom: 20px;
  z-index: 50;
  width: 100%;

  .play {
    box-sizing: border-box;
    width: 135px;
    padding: 7px 0;
    margin: 0 auto;
    text-align: center;
    border: 1px solid $color-theme;
    color: $color-theme;
    border-radius: 100px;
    font-size: 0;

    .icon-play {
      display: inline-block;
      vertical-align: middle;
      margin-right: 6px;
      font-size: $font-size-medium-x;
    }

    .text {
      display: inline-block;
      vertical-align: middle;
      font-size: $font-size-small;
    }
  }
}

.filter {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(7, 17, 27, 0.4);
}

.bg-layer {
  position: relative;
  height: 100%;
  background: $color-background;
}

.list {
  position: absolute;
  top: 262px;
  bottom: 0;
  width: 100%;
  background: $color-background;
}

.song-list-wrapper {
  padding: 20px 30px;
  margin-top :-20px;
}

.loading-container {
  position: absolute;
  width: 100%;
  top: 50%;
  transform: translateY(-50%);
}
</style>